fuel pump problem?

eran tomer · Jul 23, 2022

in my 95 5.7 suburban when turning key to ON the fuel pump is priming quite some time, maybe 10 seconds or more. the book says it should run for 2 seconds. it's a new pump, I never payed attention to this matter so I don't know/remember what it has been like before. in addition the scanner is showing about 13.3-13.4V for the pump, and a bit more for system voltage.

PlayingWithTBI · Jul 23, 2022

eran tomer said:
when turning key to ON the fuel pump is priming quite some time, maybe 10 seconds or more. the book says it should run for 2 seconds.

Maybe you have the Hot Fuel Module? FWIU GM put them in trucks with the 7.4L and some other HD ones. It's supposed to run for 30 seconds to help eliminate vapor lock.

eran tomer · Jul 23, 2022

mine is 5.7 but indeed HD with 8600 gvwr emissions. how can I tell if it has the hot fuel module?

PlayingWithTBI · Jul 23, 2022

eran tomer said:
how can I tell if it has the hot fuel module?

When it primes for more than 2 seconds :anitoof:

Sorry about that, IDK where the HFM is located, maybe someone else knows? I think it's a little box somewhere near the PCM.

GMCTruck · Jul 23, 2022

My 95 K1500 with the TBI 5.7 works like that too. I can't say how long exactly but the fuel pump primes for quite a bit longer than 2 seconds. Since it works fine, I ain't gonna question it.

Schurkey · Jul 24, 2022

Fuel pump voltage registered at the scan tool, is not the voltage the pump is actually seeing. Any voltage drop between the computer and the fuel pump, and any resistance on the ground side of that circuit, does not register on the scan tool.

Voltage has to be tested as close to the load as practical. Amperage can be tested anywhere in that circuit.

eran tomer · Jul 24, 2022

Schurkey said:
Fuel pump voltage registered at the scan tool, is not the voltage the pump is actually seeing. Any voltage drop between the computer and the fuel pump, and any resistance on the ground side of that circuit, does not register on the scan tool.

Voltage has to be tested as close to the load as practical. Amperage can be tested anywhere in that circuit.

But the spec for the scan tool reading is at least 13.5. So you say the pump sees less than the reading?

fuel pump problem?

eran tomer

I'm Awesome

PlayingWithTBI

2022 Truck of the Year

eran tomer

I'm Awesome

PlayingWithTBI

2022 Truck of the Year

GMCTruck

I'm Awesome

Schurkey

Supporting Member

eran tomer

I'm Awesome

Similar threads

Latest posts

Members online

Forum statistics

Share this page